Add feature to convert to file-scoped namespace just by typing ; after a normal namespace.

[CyrusNajmabadi]

Fixes: #57841

Feature is very simple. But if you have:

And you type ; after the namespace name, then it automatically translates you to:

This is the same thing the code-action/refactoring does. However, i've found that my intuition is to just type ;, and i think it would be nice to just have things update cleanly without having to manually delete the curlies and format the document.

[davidwengier]

I wonder if this should be dependent on the "complete statement on semicolon" option? I could see accidental activation of this being annoying. eg I expect if someone did it in Roslyn and didn't notice, the PR would not be approved 😬

[Cosifne]

Some unused comments here

[CyrusNajmabadi]

yup. will clean up

[Cosifne]

The format here is a little bit strange to me.
I feel it's more natural to see namespace N; // Goo

[CyrusNajmabadi]

@davidwengier we now respect the option around completing code with a semicolon. :)

[davidwengier]

Thank you for gating this

[sharwell]

❗ This assumes the file is formatted according to the formatter, which is not a safe assumption. This feature is only allowed to remove a uniform number of leading spaces from each line in the namespace block, and is not allowed to force potentially incorrect formatting throughout the file.

[JoeRobich]

I saw this tweet that indicated the codefix for converting to file scoped namespaces forced a format on users https://twitter.com/rickbrewPDN/status/1463361397677379590

[davidwengier]

Yah, this has come up on Discord a couple of times too, and ASP.NET ran into it too: dotnet/aspnetcore#38681 (comment)